The invention relates to calendars in general, and more particularly to improvements in calendars of the type wherein the end portions of calendar rolls forming a stack of rolls are mounted in two frame members and at least one of the rolls is movable relative to the neighboring roll or rolls. Still more particularly, the invention relates to improvements in calendars of the type wherein at least one intermediate roll is mounted on a pair of levers which are pivotably as well as otherwise movably mounted in the respective frame members so as to reduce the likelihood of stray movements of the one intermediate roll with reference to the neighboring rolls in response to pivoting of the levers.
It is often desirable to mount the intermediate rolls of a calendar on pairs of levers because the bearings for the end portions of such rolls can be moved to different levels with a minimum of friction or with no friction at all, in contrast to intermediate rolls whose bearings are mounted directly on the respective frame members. As a rule, the pivots for levers which carry the bearings for the end portions of intermediate rolls are mounted directly in the frame members. Reference may be had to U.S. Pat. No 2,850,952 to Hornbostel. It is also known to provide compensators which bear upon the levers in directions to counteract the tendency of levers to pivot under the weight of the bearings which are mounted thereon. A drawback of such calendars is that the range of the compensators is small, in part because it is not advisable to pivot the levers through relatively large angles since this would entail a lateral shifting of the respective intermediate rolls with reference to the neighboring roll or rolls. In other words, if the levers which carry the bearings for the end portions of an intermediate roll in a stack of superimposed calendar rolls are pivoted through a relatively large angle, the nip of the intermediate roll with the neighboring roll or rolls is shifted horizontally and is out of line with the other nip or nips of the stack of rolls. On the other hand, it is often desirable or necessary to move the bearings for a particularly intermediate roll through a relatively large distance, for example, if a large-diameter intermediate roll is to be replaced with a smaller-diameter intermediate roll or vice versa. It is known that larger-diameter intermediate rolls (some of which are known as filled rolls) can be used jointly with smaller-diameter metallic rolls (e.g., steel rolls). Reference may be had, for example, to U.S. Pat. No. 3,016,819 to Kupka. In many calendars, the intermediate rolls include so-called soft or elastic rolls which are provided with peripheral linings of plastic, paper or other fibrous material and must be treated from time to time in material removing machines to restore the uniformity of their diameters.
The patent to Kupka further discloses a mechanism which can be used to reduce the extent of lateral shifting of an intermediate roll as a result of pivoting of levers which carry the bearings for the end portions of such roll. The mechanism employs short links with one end portion of each link articulately connected to an intermediate portion of the adjacent lever and the other end portion of each link fulcrumed in the frame. The pivots for the levers are fixedly mounted in the respective frame members, and each lever has a slotted portion which receives the respective pivot and is slidable therealong. The patent to Kupka further discloses rather complex means for limiting the extent of pivotability of levers for the bearings at the ends of intermediate levers; such limiting means includes a stop having an elongated slot and being pivotally mounted on a retaining lever which is movable to different levels by a feed screw. The patented calendar is rather complex and it cannot adequately limit the extent of lateral shifting of intermediate rolls in response to pivoting of the respective pairs of levers. In order to reduce the need for extensive pivoting of pairs of levers which carry the bearings for the intermediate rolls, the patent proposes to employ a fixedly mounted center roll, a first stack of intermediate rolls between the center roll and the topmost roll, and a second stack of intermediate rolls between the center roll and the lowermost roll. This patent does not propose to use compensators which would counteract the tendency of pairs of levers to pivot under the weight of the bearings for the end portions of intermediate rolls.
Austrian Pat. No. 284,611 discloses a calendar wherein some of the intermediate rolls are movable transversely of the neighboring rolls. The purpose of such adjustment is to compensate for wear upon the rolls.